Hello from the North of Scotland.
Don't have a Z4 yet but hope that will change very soon.
Had a Z3 a few seconds years ago and have a 520d M-Sport as my daily runabout.
Enjoying picking up info from the forum.
Corms
I was looking at a 2.5 when I first started looking. If you look at the MPG and insurance costs for a 3.0 you will be surprised to see there pretty much the same. I regularly get over 40MPG from the 3.0.